Give the link's liveness one owner

AGENTS.md

@@ -55,12 +55,12 @@ src/
 	held-messages.ts     HeldMessages: capped, expiring messages the application has not answered, one MessageHold each
 	idle-waiters.ts      IdleWaiters: waiting for a count to fall to zero, and what is left of a budget
 	incoming-requests.ts Every request the peer sends: messages, receipts, links, unknown commands
-	link-gate.ts         LinkGate: where a request with no link to go out on waits for the next one
+	link-life.ts         LinkLife: whether the link lives, and where a request waits for the next one
 	link-timers.ts       LinkTimers: the enquire_link heartbeat and the idle timeout
 	log.ts               SmppLog, the logger contract, and silentLog — the default
 	message.ts           Encoding detection, splitting, bit counting, SMPP date formatting
 	message-body.ts      Where an inbound body is: short_message, or the message_payload TLV
-	outgoing-requests.ts OutgoingRequests: the gate, the window, the pending map and the retry
+	outgoing-requests.ts OutgoingRequests: the window, the pending map and the retry
 	pdu.ts               pduToObj / objToPdu / pduReturn — synchronous, result-returning
 	pdu-framer.ts        PduFramer: a byte stream cut into complete PDUs
 	pdu-refusal.ts       A PDU the codec would not read, and the answer SMPP names for it
@@ -314,13 +314,13 @@ the file.
 - A message id base is merged at most once.
 - A send that never reached the socket waits for the next link; one that did is counted, not resent.
 - A send queued for a send-window slot is bounded by the caller's `signal`, and by nothing else.
-- The gate decides whether a link can carry a request, and a bind is what makes it one.
+- `LinkLife` decides whether a link can carry a request, and a bind is what makes it one.
 
 ### [Internals and tests](docs/decisions.md#internals-and-tests)
 
 - #30 and #46 merged under the comprehension floor, and Locality is the next work.
 - A listener that rejects is routed by Node's `captureRejections`, not by hand-dispatching.
-- The four-line abort dance is copied across `LinkGate`, `IdleWaiters`, `PendingRequests` and
+- The four-line abort dance is copied across `LinkLife`, `IdleWaiters`, `PendingRequests` and
   `SendWindow` rather than extracted.
 - `SmppLog` is a five-method contract this library declares, not a dependency.
 - The TLS tests build their own self-signed certificate in DER